Many of us have had the opportunity to experience recent events around Hood Canal … playin', fishin', rainin', etc. Life on the canal just wouldn't be the same without the variety.

But let me take you back to this summer, when we were enjoying the calm, still, warm waters of Hood Canal. The calm surface of any water can be a deceptive distraction to the things which are happening below the surface. Critters which are accustomed to the cold waters of the canal have been struggling, and are still struggling as the seasons move towards winter.

It appears the struggle has much to do with the low levels of dissolved oxygen (DO) in the marine water. The amount of DO in the marine waters of Hood Canal are affected by many things… geology, ocean inputs, seasonal weather, tidal fluctuations, as well as nutrient contributions from rivers (uplands) and nearshore sources.

There is a unique matrix of factors contributing to the low DO events in the canal. Some factors are human influenced (nutrients) and others are not (ocean conditions, geology).

Let's put some perspective on DO levels in the water.

Critters breathing underwater breathe the same oxygen that we do. The air we breathe is comprised of about 20% oxygen. Oxygen levels can be measured in parts per million, which is to say the atmosphere (the air we breath) contains ~210,000 parts per million (Dr. W. S. Broecker, www.columbia.edu).

To put it into perspective … if you filled your room with a million ping pong balls, 210,000 of those balls would represent oxygen.

Another perspective … you're a salmon in the same room (filled with water) with the same million ping pong balls. For the oxygen level to be acceptable (for a salmon) there needs to be at least 5 balls representing oxygen. When the oxygen levels fall below 5 (8-12 is good), it creates a stress to fish. A level below 2 is considered hypoxia … a point at which most marine critters can't survive.

Oxygen levels in southern Hood Canal have been low enough below the depth of 10 meters to cause death in some marine organisms. To escape those conditions, much of the marine life (flounders, crab, shrimp, rockfish) have been observed moving toward the surface. Some of the latest DO testing shows that the low oxygen levels extend all the way to the surface.

Fish and other marine organisms just can't escape it. The prolonged and persistent low level of DO has recently shown up as fish kills.

Area residents have reported seeing hundreds of shrimp, blennies and gunnels, along with dozens of rockfish, striped perch and other fish, dead on the beach. WDFW divers, dispatched to investigate, found those and other species - including flounder and Pacific octopus - dead underwater.

In mid-September, WDFW closed fisheries for deepwater species. These seasonal low DO events in Hood Canal are not a new phenomenon, but there is a trend (measured over the last 20 years) that the low DO events are coming sooner and lasting longer.

Jan Newton, an oceanographer for the WA State Department of Ecology, explains that the reasons for this growing problem are not fully understood, but may include changes in circulation patterns resulting from river management, changes in ocean conditions, and increased nutrient levels from pollution in runoff.

Ah, the nutrient thing. Streams, tributaries, run-off, and nearshore seepages carry a nutrient load from the watershed that ultimately flows into the canal. To oversimplify, nutrients are a limiting factor in the canal. Additional nutrients essentially create a greater DO problem.

Since August, the HCSEG, with assistance from the University of Washington (UW) and Ecology, has been monitoring dissolved-oxygen levels on a weekly basis. Hood Canal will be better served when we each start to understanding where we fit into the matrix. Our collective actions likely contribute to the DO events. Be mindful of how we dispose of yard waste as well as septic and runoff effluents.

The monitoring effort could use more skippers and their boats to add to the existing team. The sampling happens on Sundays and/or Mondays and takes two to four hours. For more info call the Hood Canal Salmon Enhancement Group at (360)275-3575 or visit their website at www.hcseg.org.